1. Field of the Invention
The present invention involves a control mechanism for a tridimensional cam. A tridimensional cam receives two independent variables and provides one or more functions of these two variables. The device according to the invention can thus, for example, be used in a turbomachine regulating system.
2. Description of the Prior Art
The regulation of a turbojet requires a complex computer, one of the many capabilities of which is to calculate one or several functions of multiple variables. These can be various physical parameters, such as temperatures, flow rates, the operating speed of the turbine, etc.
There exist, of course, various types of computers capable of calculating functions of multiple variables, notably a purely electronic computer. These present the disadvantage of accepting only input values of an electrical nature, whereas the control mechanism according to the present invention accepts input values (the variables) of a fluid nature (hydraulic or pneumatic) while the output value (the function) is a translation movement which is easily convertible into a value of another given physical nature.
The control mechanism of a tridimensional cam according to the present invention is characterized by the fact that the tridimensional cam is made of a single piece with a contoured but essentially cylindrical surface and a cylindrical bore, and that this cam is displaced relative to at least one sensor by means of a composite jack which produces independent movements of the cam both around the rotational axis of the system for one of the values, in translation in the direction of this axis for the second value.
U.S. Pat. No. 2,893,210, applied for on June 17, 1958, describes the combination, in the same fixed cylinder, of a piston transmitting rectilinear movements to a rod, with a sort of rotary jack having two chambers wherein filling one or the other of these chambers with a pressurized fluid causes the rotation of a sleeve which is immobilized relative to translational movement of the aforesaid rod, but which rotates as one piece with the rod.
This existing mechanism, which has a linear-action jack combined with a rotary jack, could be used as a basis for implementing the present invention, by mounting the tridimensional cam (i.e. specifically the cylindrical part onto which the cam is mounted or tooled) on the end of the rod of the composite jack which projects from the jack housing. The resulting version, which might be useful in certain applications, would, however, be insufficiently compact in the regulator of a turbojet, since the cam and its sensor would have to be mounted on the extension of the fixed cylinder of the composite jack.